Abstract: It has always been considered that the oil in Laojunmiao oilfield was sourced from Qingxi sag by means of secondary migration, and this viewpoint has been verified by obvious lateral change of crude oil properties.However, analysing the forming time of Laojunmiao anticline combined with hydrocarbon generation and expulsion from Lower Cretaceous source rock in Qingxi sag, we discovered that the formation of Laojunmiao oilfield has a close relation with other oilfields in anticlinal belt, which is the result of secondary oil generation and remigration.Based on this viewpoint, it can be inferred there is better hydrocarbon potential in northwestern margin of Qingxi sag, new discovery is expected in oil/gas exploration over basins in the whole Altun strike-slip structural belt.

Key words: Laojunmiao oilfield, Source depression, Source bed, Secondary migration, Expelling hydrocarbon, Anticline